Undergraduate Honors Theses

Thesis Defended

Spring 2011

Document Type

Thesis

Department

Integrative Physiology

First Advisor

Kenneth P. Wright Jr., PhD

Abstract

Introduction: In modern day society, pressures from the business and academic worlds cause people to consistently self-impose sleep restriction in order to meet deadlines. To maintain a level of alertness during these periods, many individuals rely upon caffeinated beverages in order to heighten their awareness and repress their drive for sleep. However, caffeine’s wakefulness promoting properties can negatively affect sleep quality during the following night’s sleep, resulting in an individual feeling less rested upon awakening. This thesis looked at the combined effects of sleep deprivation and caffeine on daytime recovery sleep. The study design mimics staying up all night in order to meet societal demands (e.g. tests, deadlines) and thus is directly translatable to common society. Methods: Thirty drug free males and females ages 18 to 35 participated in this study. Subjects completed an in-laboratory study. Subjects were given an 8 h baseline polysomnographically recorded sleep opportunity on the first night. Following the baseline night, subjects were sleep deprived for 28 h. Ten subjects were assigned to a caffeine group and administered a caffeine pill at 23 h awake. A 5 h recovery sleep opportunity followed the sleep deprivation episode. Sleep records were visually scored and compared within subjects and between conditions. Results: Sleep deprivation significantly decreased amounts of stage 2, REM and REM latency during recovery sleep in both the caffeine and placebo groups. Caffeine, in combination with sleep deprivation, significantly increased the amount of wakefulness and decreased the amount of stage 3/4 sleep when compared to placebo. These effects were seen when comparing the entire sleep episodes as well as when comparing the first 300 minutes of each sleep episode. Conclusion: The effect of caffeine attenuates the ability to dissipate the homeostatic build-up of sleep pressure that results from extended wakefulness. This is seen as a significant interaction between caffeine and sleep deprivation in the amount of deep sleep present in the recovery sleep episode. We also see a significant increase in the percent wakefulness in the caffeine group when compared to placebo indicate that caffeine 5 hours prior to daytime recovery sleep disturbs sleep even when sleep pressure is high. The disturbed sleep findings have important implications for individuals who use caffeine to promote wakefulness at night. Support: NIH R01 HL081761

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